Historical Account of Dengue Haemorrhagic Fever in

By Tissa Vitarana, W S Jayakuru, and Nalini Withane Ministry of Science, Technology and Human Resources Development, No. 320, Jayah Mawath 10

Sri Lanka is an island situated 34 kilo- During the period 1991-1995, between metres south of India. It has an area of 440 and 1048 cases were reported each 65 610 sq km and a population of 18.3 year with a CFR of about 4%. However, in million, 22% of whom live in urban areas 1996, there was an epidemic with 1298 and the rest in rural areas. Clinical dengue- clinically-diagnosed cases of DHF hospi- like illness has been recorded in Sri Lanka talized and 54 deaths (CFR 4.2%). since the beginning of the century, and it Because of deficiencies in reporting it is was serologically confirmed in 1962. likely that the actual number of cases was Following a Chikungunya outbreak in 1965, more. there was an island-wide epidemic of dengue associated with DEN types 1 and In 1989, the DHF cases initially 2, with 51 cases of DHF and 15 deaths in occurred mainly in and around Colombo, the period 19651968. From 1969 up to but they progressively spread to other 1988, multiple dengue serotypes circulated towns and reached outbreak proportions in urban areas with endemic DF, but there in several provincial capitals, e.g. were only occasional cases of DHF. Kurunegala, , and Batticoloa in 1996. From 1989 onwards, DHF has become endemic in Sri Lanka and there The age distribution pattern shows a have been 203 hospitalized clinical cases preponderance in children under 15 of DHF, of whom 37% were serologically years (65%), with a peak in the 5-9-year confirmed and 20 deaths, giving a case age group. It is noteworthy that there has fatality rate (CFR) of 9.8% (Figure). been a significant number of cases in the There was a sharp rise in 1990 with 1350 15-29-year age group, especially bet- suspected DHF cases, of whom 363 ween 15-19 years. The sex distribution were serologically confirmed, and there does not show any significant male-to- were 54 deaths (CFR 4.0%). female difference.

Dengue Bulletin – Vol 21, 1997 117

Historical Account of Dengue Haemorrhagic Fever in Sri Lanka

Figure 1. DHF cases and positives, Sri Lanka, 1989-1996

There is a close correlation of the etc. Indoor water storage is not widely occurrence of DF/DHF with the rainfall practised in Sri Lanka. and the peak levels are reached with the south-west monsoon (May to July) and the The main serotypes associated with north-east monsoon (October to DHF since 1989 have been DEN-2 and 3. December). Entomological studies conducted by the Medical Research Institute (MRI) indicate that over 90% of References the breeding of Aedes aegypti and Aedes Anonymous : Dengue fever and DHF in Sri Lanka. albopictus occurs in small outdoor WHO/SEARO, Dengue Newsletter, 1993, 18:12. containers like tins, coconut shells, bottles, plastic containers, rubber tyres,

118 Dengue Bulletin – Vol 21, 1997